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place of origin,the period when it was used,who founded it,the unit of time which was measured by it,of sundial,sand clock.

Sand clock
The origin of the hourglass is unclear, although it may have been introduced to Europe by an 8th-century monk named Luitprand, who served at the cathedral in Chartres, France.The Sand Clock is an interactive metaphorical representation of time.A grain of sand appears each second that passes in a day. The grains slowly fill the screen until midnight, when yesterday’s sand vanishes and the cycle repeats a new.
Sundial
Babylonians and Egyptians built obelisks which moving shadows formed a kind of sundial, enabling citizens to divide the day in two parts by indicating noon.The oldest known sundial was found in Egypt and dates from the time of Thutmose III, about 1,500 years BC.At present, although the accuracy of mechanical clocks outweighed sundials, they continue be built, primarily as a decoration on buildings, monuments and public places. It is based on the fact that the shadow of an object will move from one side of the object to the other as the sun “moves” from east to west during the day.


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